wrong_code stringlengths 3 123 | correct_code stringlengths 3 155 | explanation stringclasses 101
values | language stringclasses 26
values |
|---|---|---|---|
type MyType = string | number; let x: MyType = true; | type MyType = string | number; let x: MyType = 'hello'; | Type not in union. | TypeScript |
foo == '87' | foo === 87 | Use strict equality. | JavaScript |
var x = 5; x = true | var x = 5; x = 10 | Type mismatch. | Kotlin |
System.out.println('hello') | System.out.println('hello'); | Add semicolon. | Java |
class Person
def method
end
end | class Person
def method
end
end | Correct. | Ruby |
def test
puts 'world'
end | def test
puts 'world'
end | Correct. | Ruby |
switch(y){{ case 46: break; }} | switch(y){{ case 46: break; default: break; }} | Add default case. | Java |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
{{'title':'info'}} | {{"title":"info"}} | Use double quotes. | JSON |
if (count = 60) {{}} | if (count == 60) {{}} | Use ==. | Java |
function handle(foo:string){{return foo;}} handle(50); | function handle(foo:string){{return foo;}} handle('test'); | Pass correct type. | TypeScript |
println('hello') | println("hello") | Double quotes. | Scala |
if num > 91
puts 'data' | if num > 91
puts 'data'
end | Add 'end'. | Ruby |
<img src='hello.jpg'> | <img src='hello.jpg' alt='desc'> | Add alt text. | HTML |
math.sqrt(38) | import math
math.sqrt(38) | Import module first. | Python |
object Item {{ def main(args: Array[String]) = println("test") }} | object Item {{ def main(args: Array[String]): Unit = println("test") }} | Add return type Unit. | Scala |
int x; System.out.println(x); | int x = 0; System.out.println(x); | Initialize variable. | Java |
console.log('test' | console.log('test') | Close parenthesis. | JavaScript |
assert a > 77 | assert a > 77 | Correct. | Python |
disp('value') | disp('value') | Correct. | MATLAB |
echo data hello | echo 'data hello' | Quote to prevent splitting. | Shell |
values[86] | if (values.indices.contains(86)) values[86] | Check index. | Kotlin |
<a href='https://demo.net' target='_blank'> | <a href='https://demo.net' target='_blank' rel='noopener'> | Add rel for security. | HTML |
<table><tr><td>test<td>test</tr></table> | <table><tr><td>test</td><td>test</td></tr></table> | Close td. | HTML |
let foo = 51; | let foo = 51; | Correct. | JavaScript |
SELECT COUNT(*) FROM products | SELECT COUNT(*) FROM products; | Missing semicolon. | SQL |
class User {{ int item; }}; | class User {{ public: int item; }}; | Make public. | C++ |
function process(num)
print(num)
end | function process(num)
print(num)
end | Correct. | Lua |
while read line; do echo $line; done < config.json | while read line; do echo $line; done < config.json | Correct. | Shell |
JOIN orders ON users.id = orders.status | JOIN orders ON users.id = orders.status | Correct. | SQL |
let text = String::from("value"); let r=&text; text.push_str("!"); | let mut text = String::from("value"); let r=&text; println!("{{}}", r); text.push_str("!"); | Cannot mutate while borrowed. | Rust |
process | process() | Add parentheses. | Kotlin |
if val = 66: | if val == 66: | Use == for comparison. | Python |
var x = 48; | var x = 48; | Correct. | Dart |
'value' + 73 | 'value' + str(73) | Can't add int to string. | Python |
[x*x for x in list if x > 13] | [x*x for x in list if x > 13] | Correct list comprehension. | Python |
while val > 10
val -= 1 | while val > 10:
val -= 1 | Colon missing after while. | Python |
arr[67] | if (length(arr) >= 67) arr[67] | Check length. | R |
WHERE age = '82' | WHERE age = 82 | Don't quote integer. | SQL |
var x int = 'data' | var x string = 'data' | Type mismatch. | Go |
$x = 5; if ($x -eq 5) { Write-Host 'yes' } | $x = 5; if ($x -eq 5) { Write-Host 'yes' } | Correct. | PowerShell |
if (index = 30) {{}} | if (index == 30) {{}} | Use ==. | Kotlin |
int y = 'data'; | String y = 'data'; | Type mismatch. | Dart |
<input type='text' value='world'> | <input type='text' value='world' name='status'> | Add name attribute. | HTML |
{{'status':19, 'title' 85}} | {{'status':19, 'title':85}} | Colon missing. | Python |
for (int i=0; i<5; i++) {{}} | for (int i=0; i<5; i++) {{}} | Correct. | Java |
const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(72); | const express = require('express'); const app = express(); app.get('/', (req,res) => res.send('hello')); app.listen(72, () => console.log('listening')); | Add callback. | Node.js |
<p>output <b>test</p></b> | <p>output <b>test</b></p> | Nest properly. | HTML |
match y {{ 1 => {{}} }} | match y {{ 1 => {{}} _ => {{}} }} | Match must be exhaustive. | Rust |
echo 'test' | echo 'test'; | Add semicolon. | PHP |
data.forEach(function(a) {{ console.log(a); }}) | data.forEach((a) => {{ console.log(a); }}) | Arrow functions are cleaner. | JavaScript |
if ($val = 4) | if ($val == 4) | Use ==. | Perl |
test | test() | Add parentheses. | Swift |
[58, 79, 47 | [58, 79, 47] | Close bracket. | Python |
else
print('result') | else:
print('result') | Colon after else. | Python |
for (num in data) | for (num of data) | for...in iterates keys. | JavaScript |
with open('log.txt') as fh:
data = fh.read() | with open('log.txt') as fh:
data = fh.read() | Correct. | Python |
int &ref; | int x; int &ref = x; | Reference must be initialized. | C++ |
let data: Int = 'hello' | let data: String = 'hello' | Fix type. | Swift |
for i=1,71 do print(i) end | for i=1,71 do print(i) end | Correct. | Lua |
<note name='hello'/> | <note name="hello"/> | Double quotes. | XML |
'69' + 92 | 69 + 92 | Avoid string coercion. | JavaScript |
let mut c=35; let r1=&mut c; let r2=&mut c; | let mut c=35; {{ let r1=&mut c; }} let r2=&mut c; | Only one mutable borrow. | Rust |
$arr[45] = 5; | if (isset($arr[45])) $arr[45] = 5; | Check existence. | PHP |
List(40,33,15) | List(40,33,15) | Correct. | Scala |
val temp: Int = 'output' | val temp: String = 'output' | Fix type. | Kotlin |
{{"age":"hello" "status":84}} | {{"age":"hello", "status":84}} | Add comma. | JSON |
class = 'data' | class_name = 'data' | 'class' is a keyword. | Python |
#header {{ color: blue; }} | #header {{ color: blue; }} | Correct. | CSS |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
const int x; x = 5; | const int x = 5; | Const must be initialized. | C++ |
UPDATE orders SET id='result' WHERE status=67 | UPDATE orders SET id='result' WHERE status=67; | Add semicolon. | SQL |
print 'output' | print 'output'; | Add semicolon. | Perl |
.Person {{ color: red; }} | .Person {{ color: red; }} | Correct. | CSS |
let foo: i32 = "world"; | let foo: &str = "world"; | Type mismatch. | Rust |
void main() {{ print('info') }} | void main() {{ print('info'); }} | Add semicolon. | Dart |
function test(c:string){{return c;}} test(90); | function test(c:string){{return c;}} test('world'); | Pass correct type. | TypeScript |
int main() {{ return 0; }} | int main() {{ return 0; }} | Correct. | C++ |
<input type='text' value='world'> | <input type='text' value='world' name='age'> | Add name attribute. | HTML |
String name = 'info'; | String name = 'info'; | Correct. | Dart |
if ($z = 61) {{}} | if ($z -eq 61) {{}} | Use -eq. | PowerShell |
list:
- item1
- item2 | list:
- item1
- item2 | Correct. | YAML |
{{"name":"value",}} | {{"name":"value"}} | Remove trailing comma. | JSON |
let foo = 16; foo += 1; | let mut foo = 16; foo += 1; | Need mut to modify. | Rust |
#header {{ color: #333; }} | #header {{ color: #333; }} | Correct. | CSS |
$items[26] | if ($items.Count -gt 26) {{ $items[26] }} | Check bounds. | PowerShell |
{{'name':19, 'id' 34}} | {{'name':19, 'id':34}} | Colon missing. | Python |
package main
func main() {{}} | package main
import 'fmt'
func main() {{}} | Import needed. | Go |
int a = 'output'; | String a = 'output'; | Type mismatch. | Dart |
class Order {{ int index; }}; | class Order {{ public: int index; }}; | Make public. | C++ |
System.out.println('world') | System.out.println('world'); | Add semicolon. | Java |
@media screen {{ body {{}} }} | @media screen {{ body {{}} }} | Correct. | CSS |
if (c) console.log('yes') else console.log('no') | if (c) console.log('yes'); else console.log('no'); | Missing semicolon. | JavaScript |
let index: number = 'output'; | let index: string = 'output'; | Fix type. | TypeScript |
int items[24]; items[24]=5; | int items[24]; if(24<24){{}} else items[24]=5; | Bounds check. | C++ |
div {{ color=red; }} | div {{ color: red; }} | Use colon. | CSS |
fs.readFile('config.json', (err,data) => {{ if(err) throw err; }}); | fs.readFile('config.json', (err,data) => {{ if(err) {{ console.error(err); return; }} }}); | Better error handling. | Node.js |
fn compute() -> i32 {{ 65 }} | fn compute() -> i32 {{ 65 }} | Correct. | Rust |
yield num | yield num | Correct yield. | Python |
JOIN products ON items.id = products.age | JOIN products ON items.id = products.age | Correct. | SQL |
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